1. Field of Art
The present invention relates to agricultural balers for picking up crop material such as hay or straw from the field and forming it into rectangular packages. More particularly the invention relates to means installed at the rear of the machine for receiving the formed package and depositing the same onto the field.
2. Description of Prior Art
Conventionally rectangular agricultural balers comprise a frame which is traveled on a pair of wheels over a field for picking up therefrom hay, straw or silage grass and feeding such crop material to a baling chamber in which it is compressed to parallelepiped packages under action of a plunger which reciprocates inside the baling chamber. When the packages have reached a predetermined length a tying mechanism is operated to encircle the completed package with a plurality of strands and to knot the strand ends together to form a finished bale which will be ejected out of the baler.
As the outlet of the baling chamber is at a substantial height above the field, there is a risk that bales get damaged by their fall from the baling chamber, e.g. because the impact breaks some or all of the strands. Commonly this problem has been solved by providing a guide or slide means at the exit of the baling chamber for reducing the height from which the bale is released onto the field and/or giving a wanted orientation to the bale. In the art such apparatus usually is referred to as "bale chute". Examples thereof can be found in WO-A-96/29 195 and EP-A-0 771 522.
The bale chute usually constitutes the rearmost part of the baler. Most national road regulations usually put serious constraints on such rear extensions, such that the operator is forced to pivot the bale chute upwardly before he is allowed to travel the baler from one field to another by public roads. To alleviate this task the documents cited above teach the use of a hydraulic cylinder to rotate the bale chute into its transport position. However it is observed that, once in its transport position, the apparatus still requires hydraulic pressure to keep the bale chute from returning to its lower, working position. Accidental leaks or breakage of the hydraulic lines on the baler or between the tractor and the baler will lower the bale chute which consequently forms a vehicle extension which is dangerous to the other traffic. Therefore additional means such as bolts or chains are required to lock the bale chute in its transport position. However the use of these locking means is easily neglected or forgotten, exposing the operator to hazardous situations during road travel.
Therefore there is a need for a simple, yet reliable means for raising the bale chute into its upper position and keeping it therein.
Furthermore, it has been observed that while maneuvering on a field, the tail portion constituted by the bale chute is particularly vulnerable to damages caused by collisions with objects on or around the field. In particular the deposited bales may form serious obstacles while the baler is driven backwards, e.g. to realign the pick-up to the windrow. Especially freshly deposited bales are dangerous because they are still close to the rear end of the baler and consequently hidden by the body of the baler. When the baler is driven backwards the bale chute may hit the bale on the ground and the impact may seriously deform this chute such that it becomes impossible to lift it up to its transport position. The operator usually is aware of this danger but as he is not inclined to leave the tractor at every maneuver, he usually relies on what he can see from his rear view mirrors. However, because of the baler itself blocking part of his view, he cannot always tell whether a bale has been deposited immediately behind the baler. Hence there also is a need for means informing him of such possibly hazardous situation before he reverses the baler.
There are also constraints on the level of the bale chute above the field. Sufficient clearance should be provided to prevent contact with the ground when one or both wheels of the baler runs into a hole. On the other hand too high an exit level of the chute makes the impact of the bale too great, such that it may fall apart. Even with reduced heights, problems may occur because the bale starts rotating during its fall and the acquired momentum may rotate the bale further after its edge hit the soil, thereby making the bale tip over and putting it to rest on its front end. The consequent mixture of properly deposited and upright bales on the same field later complicates the handling and collection of the bales.
Consequently, there also exists a need for a system ensuring the proper and consistent deposit of the bales, without however exposing the bale chute to increased risks of damages by contact with the ground.